Over the past century, the mouse has become the premier mammalian model system for biomedical research, particularly for nutrition and obesity research (Pomp et al., 2008). Scientists from neariy all biomedical fields have adopted the mouse as a model organism because of its close genetic and physiological similarities to humans, the ability to evaluate large populations, and the ease with which its genome can be manipulated and analyzed. Like humans, mice naturally develop (or can be induced to develop) diseases including obesity, diabetes, atherosclerosis, hypertension and cancer. The mouse models currently available for biomedical research inciude hundreds of unique inbred strains, each with their own relatively well defined disease susceptibilities, and various crosses, congenics, chromosome substitution strains and recombinant inbred lines derived from these inbred strains (Peters et al, 2007). There are thousands of genetically engineered mutants ranging from overexpression models to gene knockouts to more specialized models with targeted amino acid changes and tissue specific expression that exist to study specific contributions to disease systems and processes. Energy balance, the relationship between energy consumed (through food and drink), and energy expended (through activity and metabolic rate) play a central role in many diseases, including obesity, diabetes, athelerosclerosis, reproduction, certain cancers and some psychiatric disorders, to name few. While mouse models are important in facilitating research on the impacts of genetics, nutrition and their interaction on energy balance, the overall utility of these models is often limited due to relatively basic phenotyping capabilities. For example, many studies on obesity in mice continue to use body weight as a proxy for body fat, despite the fact that the correlation between these two traits is only -50% and can vary significantly based on genotype, gender, age. diet and exercise level (Eisen and Prasetyo, 1988). Perhaps more importantly, metabolic consequences of nutritional treatments and disease often remain the focus of speculation because the ability to drill down for accurate measures of components of energy expenditure and energy intake remain outside the scope of most researchers due to expense and technological difficulties. Our long-term obiective is to facilitate multifaceted use of mouse models to studv enerav balance bv supporting high quality and high throughput phenotyping of energy balance components, including energy intake, food preference, metabolic rate, home cage activity, voluntary exercise, glucose metabolism, gut microbiome characterization, and serial measurenrients of body fat, lean mass and bone. Towards this goal, the UNC NORC created the Animal Metabolism Phenotyping (AMP) Core Facility to provide high quality, high throughput and full-service energy balance phenotyping services to a broad array of NIH-funded biomedical researchers from across the UNC campus, including the Schools of Medicine, Public Health, Arts and Sciences and Phamnacy. Building on the legacy of Nobel Prize winner Dr. Oliver Smithies, UNC has made a major commitment to research using mouse models, culminating in the recent completion of a Vivarium, located in the new UNC Genetic Medicine Building (GMB), that has the capacity for housing approximately 45,000 mouse cages, making it one of the largest mouse research facilities in the US. In addition to housing one site of the AMP core as well as mice from many investigators across campus, the GMB Vivarium is the home to two major intemational research resources. The first is the National Center for Research Resources (NCRR) funded Mouse Mutant Regional Resource Centers, which acts as a repository for mutant strains of mice. The second is a unique and powerful emerging mouse population called the Collaborative Cross (CC), whose development and use has been funded by several diverse NIH institutes. The CC is a large panel of recombinant inbred mouse lines created from an 8-way cross of inbred strains (Churchill et al., 2004), and is the only mammalian resource that has high and uniform genome-wide variation effectively randomized across a large, heterogeneous, and reproducible population which also supports integration across environmental and biological conditions, across genotypes, across diets, and over time (Chesler et al., 2008). Unique to UNC's NORC, the AMP core will provide full service access to the CC for nutrition and nutrigenomic oriented research, providing targeted and focused opportunities for pilot projects and collection of preliminary data to be used for full proposals based on this unprecedented resource.